I’m not familiar with the internal workings of QT Pro (and not in front of my edit computer to check), but see if there’s an option button. If so, data rate is probably there. You can use Compressor to make your final file (probably an h.264 file) and have much more control. The Inspector Window allows you to change preset settings if you want (or need to). Just click through the various tabs, although, most of what you want to do is in the Encoder tab.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 2 (FCP 6.0.5, Comp 3.0.5, DVDSP 4.2.1, Color 1.0.3)
Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN